More than 10 million people are diagnosed with cancer every year in the world. Cancer has become a leading cause of death, accounting to about 13% of all deaths. According to the compiled statistics by WHO, cancer claimed the lives of more than 7.6 million people worldwide in 2008 (WHO: http://www.who.int/mediacentre/factsheets/fs297/en/index.html; retrieved on 12, Oct., 2012). It is estimated that the annual death toll will reach 13.1 million by 2030. Although numerous cancer chemotherapeutics are available today, they often have very narrow therapeutic indices and very severe side effects. In addition, cancers can and often do develop resistance to many of these drugs. The fact that there currently are no drugs available that are capable of curing cancer diseases, the discovery and development of new anticancer drugs are very much needed and the undertaking of such studies is imperative.
Obesity has become increasingly concerned in modern society. It affects nearly a third population of adults in the developed countries, and more than 1.4 billion adults were overweight in 2008 according to WHO report (http://www.who.int/mediacentre/factsheets/fs311/en/, retrieved on 14 Oct., 2012.). Many health problems such as cardiovascular diseases, type 2 diabetes, cancer and osteoarthritis are associated with obesity. Obesity is largely preventable, and in fact, it is considered to be a leading preventable cause of death in the world. However, the number of people with obesity in the world is more than doubled since 1980. Obesity, the once considered a wealthy country problem is now on the rise in low- and middle-income countries. Therefore, in many cases, treatment may become inevitable option. There is only one anti-obesity drug (orlistat) approved by the FDA for long term use. The drug has side effects associated with high blood pressure, rapid heart eat, palpitations, drug addiction, and insomnia. To develop new anti-obesity drugs is thus needed.
Cyclopeptides (cyclic peptide) are peptide compounds whose amino and carboxyl termini are linked together by a peptide bond to form a circular chain. Cyclodepsipeptides have at least one lactone linkage in place of one of the amides. A cycloheptapeptide is the cyclopeptide compound containing seven amino acid residues.
A large number of cyclopeptides have been synthesized due to their variety of biological activities including anticancer activity (Wessjohann L A, Andrade C K, Vercillo O E, Rivera D G. Macrocycli peptoids: N-alkylated cyclopeptides and depsipeptides). Many cyclopeptides have also been reported from plants (Tan N H & Zhou J. Plant cyclopeptides. Chemical Review 2006; 106: 840-895). However, cyclopeptides containing rare amino acids are seldom reported either from synthetic study or from nature. We have discovered novel plant cyclopeptides that contain a unique amino acid residue in the structure.
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